In order to obtain models of complex virtual environments, there are many solutions that make use of image-based rendering techniques. When using a set of images to represent an element in space as a billboard, there are some problems related with the shading calculations, once these elements are just planes in space. This article presents a new approach for shading objects represented by images, which divides the problem into two parts: the shading maps generation for an object with specific set of lights in the environment and real-time shading simulation for a specific observer point of view and object location.